The objective oof this research project is the detailed analysis of hypothalamic nuclear metabolism during various states of reproductive behavior and physiology. Chemical analyses will be made of specific hypothalamic nuclei which have been shown by electrical stimulation, lesion production, stereotaxic hormone implantation and hormone uptake experiments to play an important role in the neuroendocrine control of sexual behavior and reproductive physiology. Analyses of enzymes reflecting overall metabolic flow through a pathway, control point enzymes, enzymes in pathways unique to brain, lysosomal enzymes, and enzymes associated with the metabolism of putative neurotransmitters will be performed during sexual development, estrous cycle, after gonadectomy, after androgen sterilization and following morphine administration. Quantitative histochemical techniques will be used enabling enzyme measurements to be made on tissue samples weighing 10 to 50 nanograms obtained by dissection of discrete but defined nuclear areas of freeze-dried, unfixed and unstained portions of hypothalamus. Immunochemical techniques will be used to measure pituitary gonadotropins, sex hormones and hypothalamic releasing hormones in order to supplement the metabolic observations to be obtained.